1. Field of the Invention
The invention relates to explosive materials. More particularly the invention relates to insensitive explosives. Most particularly, the invention relates to melt cast mixtures of insensitive explosive materials and sensitive explosive materials.
2. Discussion of the Related Art
Explosive materials are classified under a U.S. Department of Transportation standard as hazardous materials. Explosive materials are be sub classified in one of the defined sub categories from Mass Explosion Hazard (1.1) at one end of the scale to Explosive Article, Extremely Insensitive (1.6) at the other end of the scale. The utility of an explosive is inversely related to its propensity to detonate. Utility in this sense means detonation insensitivity during handling, transportation, and storage.
Military munitions with a lower hazard classified explosives have the advantages of reduced vulnerability to sympathetic detonation, detonation during transportation and handling and detonation with extended storage and temperature cycling.
Research at Livermore National Laboratory found that formulations of nitroguanidine and triaminotrinitrobenzene (TATB) were very resistant to accidental detonation. Extensive testing of PBX-9502 (95% TATB, 5% polymer binder) resulted in a new hazard classification for Insensitive High Explosive (IHE). The discovery of insensitive high explosives significantly reduced the requirements and therefore the cost of handling and storing these materials.
The Department of Defense Explosive Safety Board established hazard classification Class 1.5 for Insensitive Explosives to identify the significant insensitivity to detonation of triaminotrinitrobenzene (TATB). New explosives have been found that have extremely low probability of round-to-round, en mass reaction of projectiles containing the explosives. Explosives in this category are classified as Extremely Insensitive Detonating Substances (EIDS) in Class 1.6. These explosives are distinguished from blasting agents.
Use of reduced hazard classification explosives in conventional projectiles provides substantial advantages in operational readiness, sustainability, and survivability due to their reduced quantity distance (QD) storage and handling requirement restrictions and vulnerability. The use of detonation insensitive explosives also reduces the exposure of the public to potential hazard during transportation of munitions over public roadways.
Ammonium nitrate has been used in low melting point explosive compositions. The physical properties of ammonium nitrate present a number of disadvantages in explosives. It is hydroscopic which presents a maintenance problem over the storage life. It also requires a phase stabilizer which adds parasitic weight to any formulation and dilutes explosive performance. Other nitrate salts have also been used as explosives, but they have an excess of fuel or some other disadvantage.
There is a need in the art for an explosive composition with reduced sensitivity to impact, friction, and shock. Sensitivity results in vulnerability of rounds, projectiles, bombs and warheads to cook-off, premature reaction and round-to-round propagation (mass, detonation), and reactivity to the impact of bullets, high velocity fragments, shape charge jets, electrostatic discharge and heat.